What is in the bonus chests you get from the Breath of the Wild DLC?

The content of the 3 chests :

  • 1 Ruby
  • 5x Bomb Arrows
  • Nintendo Switch Shirt for Link to wear

That's what one player found, but as there's only the Switch Shirt which was announced, I think 'useful items' in the two others chests might also mean 'random useful items'.

Source